Binocular
The present invention relates to a binocular, and more particularly, to a binocular including diopter correction mechanisms.
Conventionally, a binocular includes two telescope systems, left and right. Each telescope system has, respectively, a plurality of optical systems. The plurality of optical systems includes an objective optical system, an eyepiece optical system and other optical systems.
In a focusing process, some of the optical systems provided in the two telescope systems cooperate laterally, and are simultaneously moved along an optical axis. For example, the right and left eyepiece optical systems are made to approach to/move away from the respective objective optical systems.
On the other hand, a diopter correction, upon the usual (user-adjusted) operation, is performed by moving some part of the optical systems of only one of the two telescope systems along the optical axis. For example, one of the objective optical systems is moved along the optical axis to correct for diopter variation from left to right in a user""s eyesight.
In such a binocular, the optical system for the diopter correction (in the above example, in the objective optical system) has additional correction length (the objective additionally movable along the optical axis) for the side upon which diopter correction is implemented(left or right) . Therefore, the optical system on one side, left or right, is longer than the other optical system by the additional correction length.
Moreover, fine adjustment of a diopter difference between left and right sides in a manufacturing process (before shipment of the binocular) requires still more movable length along the axis. Therefore, in the conventional binocular having such correction, the optical system for assembly-time or manufacturing diopter correction requires even more additional movable length than the adjustable length for the diopter correction on the usual (user adjusted) operation.
As mentioned above, if only one optical system has one diopter correction mechanism, the movable length necessary for diopter correction becomes longer, so that the size of the binocular can not be reduced.
It is therefore an object of the invention to reduce the size of a binocular by reducing a length of a telescope system along an optical axis direction.
A binocular according to the invention includes two parallel telescope optical systems, each of the two telescope optical systems having a plurality of optical systems in parallel to an optical axis. Each of the two telescope optical systems includes a first optical system in which a portion of the plurality of optical systems are moved along the optical axis for a diopter correction. Two diopter correction structures for the diopter correction are separately and independently provided in each of the two telescope optical systems by means of moving the first optical systems along the optical axis direction. Only one of the diopter correction structure includes a manually operable member exposed outward of an outer body housing of the binocular for the diopter correction.
Optionally, the first optical system of the other diopter correction structure is fixed to be unmovable along the optical axis after the diopter correction is finished.
Further, each of the two telescope optical systems may include a second optical system independent from the first optical system, which moves together with the first along the optical axis for focusing.
The first optical system may be an objective optical system, in which case the second optical system is an eyepiece optical system.
Still further optionally, the one of the diopter correction structures includes a first eccentric member integrally provided with a first shaft portion, and a first eccentric portion, eccentric to the first shaft portion. In this case, the first eccentric member may be rotatable about the axis of the first shaft portion, and engages with the first optical system. The first optical system is moved along the optical axis direction while engaging with the first eccentric member by the eccentric rotation of the first eccentric member about the axis of the first shaft portion. Optionally, the operable member includes the first eccentric member.
The other or second diopter correction structures may include a second eccentric member integrally provided with a second shaft portion, and a second eccentric portion, eccentric to the second shaft portion. In this case, the second eccentric member is rotatable about the axis of the second shaft portion, and is engaged with the other first optical system. The other first optical system is moved along the optical axis direction while engaging the second eccentric member, by the eccentric rotation of the second eccentric member about the axis of the second shaft portion.
Additionally, the binocular may include a supporting member, movably supporting the first optical system of the other telescope optical system along the optical axis direction. A shaft receiving hole is provided in the supporting member to rotatably support the second shaft portion, and the second eccentric member is rotated while the second shaft portion is supported in the shaft receiving hole.
The second shaft portion of the second eccentric member may be removable from the shaft receiving hole.